Epidemiologic and mechanical studies suggest that cyclic loading (i.e. vibration) is an important etiologic risk factor in the development of degenerative disc disease. Posture, spinal stiffness, asymmetric spinal loading, and abdominal tone appear to influence the effects of vibration. Disability is more common in patients with certain personality traits. By analysis of a general practice population and questionnaire survey, we are defining the role of cyclic loading in the broader perspective of low back pain (LBP). Subgroups with and without back pain, with and without significant vibrational loadings are being identified. These subgroups are to be investigated by questionnaire and by standardized physical examination for spinal stiffness, posture, straight leg raising, and neurologic abnormality. Psychologic factors will be evaluated by computerized modified Minnesota Multiphasic Personality Inventory (MMPI) and pain drawing. Objective radiographic analysis will correlate low back pain with postural, congenital, disc space height and facet characteristics. By case studies, the environmental vibrational stresses, lifting requirements, and asymmetric loading configurations imposed on the spine will be analyzed. The role of vibration will be further studied in the laboratory using a vibration simulator. Exposure particular at risk populations will be studied using a vibration exposure meter. Safety recommendations will be given for vibrational loadings.